12-08-2017, 01:42 PM
A practical electric power source which is a linear electric circuit may, according to Thévenin's theorem, be represented as an ideal voltage source in series with an impedance. This impedance is called the internal resistance of the source. When the power supply supplies power, the measured voltage output is less than the no-load voltage; The difference is the voltage drop (the product of current and resistance) caused by the internal resistance. The concept of internal resistance applies to all types of electrical sources and is useful for analyzing many types of electrical circuits.
Factors affecting the internal resistance of a cell:
I) The greater the separation between the electrodes of the cell, the longer the electrolyte through which the current has to flow and, consequently, a higher value of the internal resistance
Ii) The higher the conductivity of the electrolyte, the lower the internal resistance of the cell. That is, the internal resistance depends on the nature of the electrolyte.
Iii) The internal resistance of a cell is inversely proportional to the common area of the electrodes that immerse in the electrolyte.
Iv) The internal resistance of a cell depends on the nature of the electrodes.RE rI IE = V + v= IR + Ir= I (R + r) I = E / (R + r) . This relationship is called the circuit equation.
Factors affecting the internal resistance of a cell:
I) The greater the separation between the electrodes of the cell, the longer the electrolyte through which the current has to flow and, consequently, a higher value of the internal resistance
Ii) The higher the conductivity of the electrolyte, the lower the internal resistance of the cell. That is, the internal resistance depends on the nature of the electrolyte.
Iii) The internal resistance of a cell is inversely proportional to the common area of the electrodes that immerse in the electrolyte.
Iv) The internal resistance of a cell depends on the nature of the electrodes.RE rI IE = V + v= IR + Ir= I (R + r) I = E / (R + r) . This relationship is called the circuit equation.